NORTHWEST WEATHER WATCH
Experiment #4: Just a Bag of Hot Air
You can fill out this Lab Sheet
on the computer and send it to your teacher's email address by clicking
on the submit button when you are finished. Or click on this version,
print it out, and fill it in by hand.
Question: How can you inflate a balloon without blowing into it?
In this activity you will be using three simple materials to
inflate a balloon without actually blowing into it. Your
task is to figure out how to do this and then to explain why
your experiment worked (i.e. what caused the balloon to
inflate even though no new air was pumped into it).
You will need a balloon
a narrow-necked bottle
a pan of hot water
1 Lab Sheet
for each group:
Did your experiment work?
- Devise a way to inflate your balloon with the
- Record your plan in the hypothesis section of
the Lab Sheet. (We will inflate the balloon by......)
- Record the steps of your procedure and your
observations onto the Lab Sheet.
If not, devise another way to inflate your
balloon. If you succeeded in inflating the balloon, go to Hypothesis
Revisited and explain what you think caused your balloon to inflate.
Following the class discussion, your group should reassemble and
decide upon your concluding hypothesis
(i.e. how to inflate the balloon with the given materials and why this